Cell phone

ABSTRACT

In a cellular phone terminal foldable by a hinge and including upper and lower split pieces, monopole antennas are formed on a flexible printed wiring board and a printed wiring board and a lower housing is formed with a finger grip portion such that not only deterioration of characteristics is prevented but the lower housing can be held easily.

TECHNICAL FIELD

[0001] The present invention generally relates to cellular phoneterminals and more particularly, to a foldable cellular phone terminal.

BACKGROUND ART

[0002] An example of a conventional foldable cellular phone terminal isshown in FIGS. 8A and 8B. In FIGS. 8A and 8B, “801” denotes an upperhousing, “802” a lower housing “803” a hinge, “804” an upper printedboard, “805” a lower printed board, “806” a flexible printed wiringboard, “807” an external antenna, “808” a strip line antenna, “809” anupper connector, “810” a lower connector and “811” a feeding point forthe strip line antenna 808.

[0003] In the upper and lower housings 801 and 802 acting as two splitpieces folded on each other by the hinge 803 in the arrangement shown inFIGS. 8A and 8B, a portion of a conductive pattern line on the flexibleprinted wiring board 806 for electrically connecting the upper printedboard 804 and the lower printed board 805 is used as the strip antenna808 and a portion of the upper connector 809 acts as the feeding point811 for the strip line antenna 808 as disclosed in Japanese PatentLaid-Open Publication No.

[0004] Meanwhile, FIGS. 9A and 9B show an example of an arrangement inwhich an external antenna used for both transmission and reception isprovided in a lower housing. In FIGS. 9A and 9B, “901” denotes an upperhousing, “902” a lower housing, “903” a hinge, “904” an upper printedboard, “905” a lower printed board, “906” a flexible printed wiringboard, “907” an external antenna, “908” a built-in antenna, “909” anupper connector and “910” a lower connector. In this case, the built-inantenna 908 is provided in the lower housing 902.

[0005] Furthermore, FIGS. 10A and 10B show an example of an arrangementin which one turn of a flexible printed wiring board is passed through ahinge. In FIGS. 10A and 10B, “1001” denotes an upper housing, “1001 a” afront casing of the upper housing 1001, “1001 b” a rear cover of theupper housing 1001, “1001 c” a hinge of the upper housing 1001, “1001 d”and “1001 e” semicircular hinges of the upper housing 1001, “1002” alower housing, “1002 a” a front casing of the lower housing 1002, “1002b” a rear cover of the lower housing 1002, “1002 c” a hinge of the lowerhousing 1002, “1002 d” and “1002 e” semicircular hinges of the lowerhousing 1002, “1003” an external antenna, “1004” a receiver, “1005” adisplay unit, “1006” dial buttons, “1007” a transmitter, “1008” aflexible printed wiring board and “1009” a coaxial cable. In this case,the upper housing 1001 provided with the external antenna 1003 and thereceiver 1004 and the lower housing 1002 provided with the transmitter1007 are rotated about an axis of the hinges 1001 c and 1002 c so as tobe folded on each other.

[0006] The semicircular hinges 1001 d and 1001 e disposed at a centralportion of the hinge 1001 c and the semicircular hinges 1002 d and 1002e disposed at a central portion of the hinge 1002 c are formed hollowly.One turn of the flexible printed wiring board 1008 is passed along aninside diameter of the semicircular hinges 1001 d, 1001 e, 1002 d and1002 e, while the coaxial cable 1009 is inserted into the turn of theflexible printed wiring board 1008 and extends along the flexibleprinted wiring board 1008 so as to be connected to the external antenna1003 as disclosed in Japanese Patent Laid-Open Publication No. 6-311216(1994).

[0007] However, in the conventional cellular phone terminal shown inFIGS. 8A and 8B, such a problem arises that since shape of the stripline antenna 808 formed on the flexible printed wiring board 806 changesgreatly between a folding state and an unfolding state of theconventional cellular phone terminal, its impedance characteristicschange extraordinarily. In addition, in case element duration is equalto about (λ/2), such a drawback is also incurred that since electriccurrent is concentrated at the strip line antenna 808, introduction ofnoise into other signal conductor lines becomes intense.

[0008] Meanwhile, in case the built-in antenna 908 is provided in thelower housing 902 as shown in FIGS. 9A and 9B, the lower housing 902 isusually gripped by a hand when the prior art cellular phone terminal isheld by the hand, so that deterioration of characteristics of thebuilt-in antenna 908 becomes heavier disadvantageously.

[0009] Moreover, in case a strip line antenna is formed on the flexibleprinted wiring board 1008 and element duration is not more than (λ/2) inthe known arrangement of FIGS. 10A and 10B in which one turn of theflexible printed wiring board 1008 is passed along an inside diameter ofthe hollow formed at the central portion of the hinges 1001 c and 1002 cso as to be passed therethrough, electric currents flow in oppositedirections on the strip line antenna wound one turn so as to cancel eachother, thereby resulting in inconvenient drop of radiant efficiency.

DISCLOSURE OF INVENTION

[0010] The present invention has for its object to provide a foldablecellular phone terminal in which the above mentioned drawbacks of priorart are eliminated.

[0011] In order to accomplish the object, a cellular phone terminal ofthe present invention is characterized in that monopole antennas areformed on a flexible printed wiring board and printed boards connectedfoldably by the flexible printed wiring board. Meanwhile, in anarrangement in which one turn of the flexible printed wiring board iswound around a hinge, there is a feature that the monopole antennas arespaced away from an external antenna. Furthermore, there is anotherfeature that a finger grip portion is provided on a lower housing.

BRIEF DESCRIPTION OF DRAWINGS

[0012]FIGS. 1A and 1B are, respectively, a cutaway front elevationalview and a longitudinal sectional view showing an arrangement of acellular phone terminal according to a first embodiment of the presentinvention.

[0013]FIGS. 2A and 2B are, respectively, a front elevational view and atransverse sectional view showing an arrangement of a flexible printedwiring board employed in the cellular phone terminal of FIG. 1.

[0014]FIGS. 3A and 3B are, respectively, a front elevational view and atransverse sectional view showing an arrangement of a flexible printedwiring board employed in a cellular phone terminal according to a secondembodiment of the present invention.

[0015]FIGS. 4A and 4B are, respectively, a front elevational view and atransverse sectional view showing an arrangement of a flexible printedwiring board which is a modification of the flexible printed wiringboard of FIG. 3.

[0016]FIGS. 5A and 5B are, respectively, cutaway front elevational viewsshowing an arrangement and a hand-held state of a cellular phoneterminal according to a third embodiment of the present invention.

[0017]FIGS. 6A and 6B are, respectively, cutaway front elevational viewsshowing arrangements of cellular phone terminals which are first andsecond modifications of the cellular phone terminal of FIG. 5.

[0018]FIGS. 7A and 7B are, respectively, a cutaway front elevationalview and a longitudinal sectional view showing an arrangement of acellular phone terminal according to a fourth embodiment of the presentinvention.

[0019]FIGS. 8A and 8B are, respectively, a cutaway front elevationalview and a longitudinal sectional view showing an arrangement of a firstprior art cellular phone terminal.

[0020]FIGS. 9A and 9B are, respectively, a cutaway front elevationalview and a longitudinal sectional view showing an arrangement of asecond prior art cellular phone terminal.

[0021]FIGS. 10A and 10B are, respectively, a perspective view and afragmentary exploded perspective view showing an arrangement of a thirdprior art cellular phone terminal.

[0022]FIGS. 11A and 11B are, respectively, a cutaway rear elevationalview and a longitudinal sectional view showing an arrangement of acellular phone terminal according to a fifth embodiment of the presentinvention.

[0023]FIGS. 12A and 12B are, respectively, a cutaway rear elevationalview and a longitudinal sectional view showing an arrangement of acellular phone terminal according to a sixth embodiment of the presentinvention.

[0024]FIGS. 13A and 13B are, respectively, a cutaway rear elevationalview and a longitudinal sectional view showing an arrangement of acellular phone terminal which is a first modification of the cellularphone terminal of FIG. 12.

[0025]FIGS. 14A and 14B are, respectively, a cutaway rear elevationalview and a longitudinal sectional view showing an arrangement of acellular phone terminal which is a second modification of the cellularphone terminal of FIG. 12 and FIG. 14C is a schematic rear elevationalview of an upper housing of this cellular phone terminal.

[0026]FIGS. 15A and 15B are, respectively, a cutaway rear elevationalview and a longitudinal sectional view showing an arrangement of acellular phone terminal which is a third modification of the cellularphone terminal of FIG. 12.

BEST MODE FOR CARRYING OUT THE INVENTION

[0027] (First embodiment)

[0028] Hereinafter, a first embodiment of the present invention isdescribed with reference to FIGS. 1A and 1B and FIGS. 2A and 2B. FIGS.1A and 1B show an example of an arrangement of a cellular phone terminalaccording to the first embodiment of the present invention. In FIGS. 1Aand 1B, “101” denotes an upper housing, “102” a lower housing, “103” ahinge, “104” an upper printed board, “105” a lower printed board, “106”a flexible printed wiring board, “107” an external antenna, “108” aconductive pattern, “109” an upper connector, “110” a lower connectorand “111” an antenna feeding point.

[0029]FIGS. 2A and 2B shows an example of an arrangement of the flexibleprinted wiring board 106 of FIGS. 1A and 1B. In FIGS. 2A and 2B, “201”denotes an antenna conductive pattern, “202” a conductive pattern, “203”an upper cover film and “204” a lower cover film. At this time, amonopole antenna is constituted by the antenna conductive pattern 201 onthe flexible printed wiring board 106 and the conductive pattern 108 andis fed from the antenna feeding point 111 on the lower printed board105.

[0030] In case a length of the monopole antenna is set at about (λ/2),electric current on the lower printed board 105 decreases, so that itwill be possible to restrain deterioration of characteristics, which iscaused by holding the lower housing 102 with a hand. In addition, incase a length of the flexible printed wiring board 106 is not more thanone fourth of a wavelength, antinode of standing wave in currentdistribution on the antenna is present on the conductive pattern 108. Insuch a case, since radiant characteristics of the monopole antenna aresubstantially determined by the conductive pattern 108, changes of theradiant characteristics upon unfolding and folding of the cellular phoneterminal can be lessened. Furthermore, since node of standing wave incurrent distribution is present in the neighborhood of the antennafeeding point 111, changes of current distribution upon unfolding andfolding of the cellular phone terminal are small, so that it will bepossible to restrain changes of impedance characteristics. In addition,since electric current on the flexible printed wiring board 106decreases, introduction of noise into other signal conductor lines canbe restrained than that of prior art.

[0031] Meanwhile, in this embodiment, the flexible printed wiring board106 is connected to the upper and lower printed boards 104 and 105 bythe upper and lower connectors 109 and 110, respectively by way ofexample. However, it is needless to say that the flexible printed wiringboard 106 may be formed integrally with the upper and lower printedboards 104 and 105. Especially, when the upper printed board 104 and theflexible printed wiring board 106, which include the monopole antenna,are formed integrally with each other, it is possible to upgrade degreeof freedom of design of the monopole antenna.

[0032] Meanwhile, if a passive element is provided adjacent to a wholeor a portion of the monopole antenna of this embodiment, elementduration of the monopole antenna can be shortened but the monopoleantenna operates in the same mechanism as this embodiment.

[0033] Also in case a microstrip line is formed by bringing ground closeto a portion of the monopole antenna of this embodiment, the sameeffects as those of this, embodiment can be gained.

[0034] Meanwhile, in case a great influence of introduction of noiseinto other signal conductor lines is exerted by an antenna element onthe flexible printed wiring board 106, it is considered that amicrostrip line is formed by bringing ground close to a portion or awhole of the antenna element on the flexible printed wiring board 106.In this case, the antenna element on the flexible printed wiring board106 may function as a part of the monopole antenna.

[0035] It is to be noted that the monopole antenna is not necessarilyused exclusively for reception. In this embodiment, the monopole antennais used in combination with the external antenna 107 as an example.However, it is needless to say that the monopole antenna can be used forboth transmission and reception. In this case, it is possible to performdiversity reception by combining the monopole antenna with anotherbuilt-in antenna.

[0036] Meanwhile, position of the external antenna 107 is not restrictedto that shown in FIGS. 1A and 1B and it is natural that only a built-inantenna may also be provided by eliminating the external antenna 107.

[0037] (Second embodiment)

[0038] Hereinafter, a second embodiment of the present invention isdescribed with reference to FIGS. 3A and 3B. FIGS. 3A and 3B show anexample of an arrangement of a flexible printed wiring board 106employed in a cellular phone terminal according to the second embodimentof the present invention. In FIGS. 3A and 3B, “301” denotes an antennaconductive pattern, “302” an upper conductive pattern, “303” a lowerconductive pattern, “304” an upper cover film, “305” an intermediatecover film and “306” a lower cover film.

[0039] In FIGS. 4A and 4B showing a modification of the flexible printedwiring board 106 of FIG. 3, “401” denotes an antenna conductive pattern,“402” a first conductive pattern, “403” a second conductive pattern,“404” a third conductive pattern, “405” a first cover film, “406” asecond cover film, “407” a third cover film and “408” a fourth coverfilm.

[0040] Meanwhile, in this embodiment, the antenna conductive patterns301 and 401 are, respectively, formed in the same layers as those of theconductive patterns 302 and 403 by way of example but the presentinvention is not restricted to this arrangement.

[0041] In FIGS. 3A and 3B, a microstrip line is constituted by the upperconductive pattern 302 acting as a signal conductor line and the lowerconductive pattern 303 acting as a ground wire. By this arrangement, itis possible to lessen the influence of noise introduction exerted by theantenna, etc., which is effective for a case in which thickness of theflexible printed wiring board 106 is limited by its hardness orstrength.

[0042] In FIGS. 4A and 4B, a triplate line is formed in which the secondconductive pattern 403 acting as a signal conductor line is interposedbetween the first and third conductive pattern 402 and 404 each actingas a ground wire. By this arrangement, the influence of noiseintroduction exerted by the antenna, etc. can be further lessened thanthat of FIGS. 3A and 3B.

[0043] Meanwhile, if a passive element is provided adjacent to a wholeor a portion of the antenna conductive pattern of this embodiment,element duration of the monopole antenna can be shortened but themonopole antenna operates in the same mechanism as this embodiment.

[0044] Meanwhile, in order to shorten element duration of the monopoleantenna, it is considered that ground is brought close to a portion ofthe antenna conductive pattern in the same manner as the firstembodiment and thus, introduction of noise into other signal conductorlines can be restrained effectively.

[0045] (Third embodiment)

[0046] Hereinafter, a third embodiment of the present invention isdescribed with reference to FIGS. 5A and 5B. FIGS. 5A and 5B show anexample of an arrangement of a cellular phone terminal according to thethird embodiment of the present invention, in which a concavely recessedfinger grip is provided in a lower housing. In FIGS. 5A and 5B, “501”denotes an upper housing, “502” a lower housing, “502 a” a first fingergrip portion, “502 b” a second finger grip portion, “503” a hinge, “504”an external antenna, “505” an upper printed board, “506” a lower printedboard, “507” a built-in antenna, “508” a flexible printed wiring board,“509” an upper connector, “510” a lower connector and “511” a left hand.In this embodiment, the cellular phone terminal is held by the left hand511 by way of example but may be, needless to say, held by a right hand.

[0047] In FIGS. 6A and 6B showing first and second modifications of thecellular phone terminal of FIG. 5, respectively, “601” and “605” denotelower housings, “601 a” and “605 a” finger grip portions, “602” and“606” hinges, “603” a lower printed board, “604” an upper housing.

[0048] In the arrangement of FIGS. 5A and 5B, the external antenna 504and the built-in antenna 507 are provided in the upper housing 501. Onthe other hand, in the arrangements of FIGS. 6A and 6B, the externalantenna 107 is provided in the lower housings 601 and 605 and a monopoleantenna is formed on the upper printed board 104 and the flexibleprinted wiring board 106. In this case, grounds of the upper printedboards 505 and 104 and the lower printed boards 506 and 603 areelectrically connected to each other only by ground wires of theflexible printed wiring boards 508 and 106 and thus, the upper printedboards 505 and 104 and the lower printed boards 506 and 603 are in avery weak grounding state.

[0049] In such a case, it is considered that grounds of the upperhousings 501 and 101 and the lower housings 502 and 601 are not commonwith each other. Namely, when the lower housings 502 and 601 are held bya hand, it can be expected that characteristics of the external antenna504 and the built-in antenna 507 provided in the upper housing 501 donot deteriorate. Likewise, when the lower housing 601 is held by a hand,it can be expected that characteristics of the monopole antenna providedin the upper housing 101 do not deteriorate.

[0050] When a conventional foldable cellular phone terminal has beenunfolded, the conventional cellular phone terminal takes a straightshape as shown in FIGS. 8A and 8B and thus, is held at differentpositions by users. Thus, by providing the concave first finger gripportion 502 a or the concave second finger grip portion 502 b on thelower housing 502 as shown in FIGS. 5A and 5B, position for holding thecellular phone terminal can be restricted to the lower housing 502, sothat it is possible to prevent deterioration of antenna characteristicsdue to holding of the cellular phone terminal by a hand.

[0051] Meanwhile, in this embodiment, the concave finger grip portionsare provided at an upper portion of the lower housing as an example butare not limited to this example. Hence, it is needless to say that thesame effect can be gained also by widening a lower portion of the lowerhousing relative to a neighborhood of the hinge of the lower housing.

[0052] Meanwhile, the finger grip portion may have such a shape as thefinger grip portion 605 a in FIG. 6B. In this case, if the upper housing604 having a shape corresponding to that of the lower housing 605 isprovided, design of the folded cellular phone terminal is upgraded. Inaddition, if a convex projection is provided on the hinge 606, thefinger can readily grip the finger grip portion 605 a.

[0053] If the cellular phone terminal is designed to a shape associatedwith a shell or an egg, a width of the neighborhood of the hingenaturally can be made narrower than a maximum width of the hosing. Inthis case, the neighborhood of the hinge of the lower housing isconsidered to function as a finger grip portion.

[0054] Meanwhile, if in addition to the finger grip portion of the lowerhousing, a neighborhood of the hinge of the upper housing is formed intoa shape similar to that of the finger grip portion, it can be expectedthat an upper limit for holding the cellular phone terminal is set. Thissetting of the upper limit is especially useful for a case in which thecellular phone terminal is of small size.

[0055] In this embodiment, the finger grip portion is concave asobserved in a front elevational view of FIG. 5A by way of example butmay be naturally provided also on a rear face of the cellular phoneterminal.

[0056] The monopole antenna is not necessarily used exclusively forreception. In this embodiment, the monopole antenna is used incombination with the external antenna by way of example but can be,needless to say, used for both transmission and reception. In this case,it is possible to perform diversity reception by combining the monopoleantenna with another built-in antenna.

[0057] Meanwhile, position of the external antenna is not restricted tothe illustrated ones and only the built-in antenna may be naturallyemployed by eliminating the external antenna.

[0058] (Fourth embodiment)

[0059] Hereinafter, a fourth embodiment of the present invention isdescribed with reference to FIGS. 7A and 7B. FIGS. 7A and 7B show anexample of an arrangement of a cellular phone terminal according to thefourth embodiment of the present invention. In FIGS. 7A and 7B, “701”denotes a hinge, “702” a flexible printed wiring board, “702 a” a firstconductive pattern, “702 b” a second conductive pattern and “703” asecond antenna conductive pattern.

[0060] In this arrangement, one turn of the flexible printed wiringboard 702 is passed along an inside diameter of a hollow of the hinge701. At this time, it is vital that the flexible printed wiring board702 should be disposed such that the external antenna is distant fromthe first conductive pattern 702 a and the antenna conductive pattern703 which constitute a monopole antenna. Namely, it is vital that thelower connector 110 should be disposed more leftwards than the upperconnector 109 in case the external antenna 107 is disposed at a leftportion of the lower housing 102. As a result, since the externalantenna 107 can be made distant from the monopole antenna, thecoefficient of correlation decreases and thus, diversity gain isupgraded. Furthermore, in this case, it is considered that the effectsare heightened by disposing the antenna conductive pattern 703 at aright portion of the flexible printed wiring board 702.

[0061] In this embodiment, the external antenna 107 is disposed at theleft portion of the lower housing 102 as an example but is notrestricted to this example. Also when the external antenna 107 isdisposed at a right portion or an upper portion of the lower housing102, the same effects can be, needless to say, achieved by making theexternal antenna 107 distant from the monopole antenna.

[0062] Meanwhile, in this embodiment, the flexible printed wiring board702 is wound one turn as an example but is not restricted to thisexample. Also when the flexible printed wiring board 702 is not woundone turn, the same effects can be, needless to say, gained by making theexternal antenna 107 distant from the monopole antenna.

[0063] The monopole antenna is not necessarily used exclusively forreception. In this embodiment, the monopole antenna is used incombination with the external antenna by way of example but can be,needless to say, used for both transmission and reception. In this case,it is possible to perform diversity reception by combining the monopoleantenna with another built-in antenna.

[0064] Meanwhile, position of the external antenna is not restricted tothe illustrated one and only the built-in antenna may be naturallyemployed by eliminating the external antenna.

[0065] (Fifth embodiment)

[0066] Hereinafter, a fifth embodiment of the present invention isdescribed with reference to FIGS. 11A and 11B in which parts similar tothose of FIGS. 1A and i B are designated by their reference numerals.FIGS. 11A and 11B show an example of an arrangement of a cellular phoneterminal according to the fifth embodiment of the present invention. InFIGS. 11A and 11B, “1101” denotes a portable radio device, “1102” amatching circuit portion, “1103” a first switching circuit, “1104” asecond switching circuit, “1105” a first matching circuit, “1106” asecond matching circuit, “1107” an antenna feeding point and “1108” adisplay.

[0067] By way of example, a case is described in which the cellularphone terminal is operated at two frequencies f1 and f2 on thesupposition that the frequencies f1 and f2 have a relation of (2f1≈f2).In case the cellular phone terminal is operated at the frequency f1, alength of the conductive pattern 108 and the antenna element on theflexible printed wiring board 106 is preset at an electric length ofabout (λ/4). In this case, the first switching circuit 1103 iscontrolled so as to conduct terminals 1103 a and 1103 b to each otherand the second switching circuit 1104 is controlled so as to conductterminals 1104 a and 1104 b to each other.

[0068] Meanwhile, at the frequency f1, the first matching circuit 1105is arranged to attain conjugated matching of an impedance in which thecircuit is observed from the antenna feeding point 1107. At the time oftransmission, a signal having the frequency f1 is inputted from theantenna feeding point 1107 to the terminal 1104 a of the secondswitching circuit 1104 so as to be applied to the first matching circuit1105 via the terminal 1104 b. An output signal from the first matchingcircuit 1105 is inputted to the terminal 1103 b of the first switchingcircuit 1103 and is radiated, through the terminal 1103 a, to space fromthe antenna element on the flexible printed wiring board 106 and theconductive pattern 108. At the time of reception, the signal having thefrequency f1 follows the path of transmission reversely so as to beinputted to the antenna feeding point 1107. At this time, since theantenna element on the flexible printed wiring board 106 and theconductive pattern 108 act as a (λ/4) monopole antenna, characteristicsof wider band can be obtained as compared with those of a (λ/2) monopoleantenna.

[0069] Then, in case the cellular phone terminal is operated at thefrequency f2, the first switching circuit 1103 is controlled so as toconduct terminals 1103 a and 1103 c to each other and the secondswitching circuit 1104 is controlled so as to conduct terminals 1104 aand 1104 c to each other. Meanwhile, at the frequency f2, the secondmatching circuit 1106 is arranged to attain conjugated matching of animpedance in which the circuit is observed from the antenna feedingpoint 1107. At the time of transmission, a signal having the frequencyf2 is inputted from the antenna feeding point 1107 to the terminal 1104a of the second switching circuit 1104 so as to be applied to the secondmatching circuit 1106 via the terminal 1104 c. An output signal from thesecond matching circuit 1106 is inputted to the terminal 1103 c of thefirst switching circuit 1103 and is radiated, through the terminal 1103a, to space from the antenna element on the flexible printed wiringboard 106 and the conductive pattern 108. At the time of reception, thesignal having the frequency f2 follows the path of transmissionreversely so as to be inputted to antenna feeding point 1107. At thistime, since the antenna element on the flexible printed wiring board 106and the conductive pattern 108 act as a (λ/2) monopole antenna, quantityof electric current flowing through the board can be lessened ascompared with that of a (λ/4) monopole antenna.

[0070] When the antenna acting as a (λ/4) monopole antenna is operatedas a (λ/4) monopole antenna, its resonance can be obtained at thedifferent frequencies by effecting changeover of the matching circuitsas described above. Especially, since an antenna of a (λ/4) resonancesystem can achieve characteristics of wider band as compared with thoseof an antenna of a (λ/2) resonance system, the resonance is suitable fora case in which in a plurality of the frequencies, the lower frequencyhas a wide band. For example, the resonance is suitable for a compositedevice having a 800-MHz band and a 1.5-GHz band in personal digitalcellular (PDC) system and a composite device of PDC system and widebandcode division multiple access (W-CDMA) system. Since quantity ofelectric current flowing through the housing or the board can belessened by the antenna of the (λ/2) resonance system more than theantenna of the (λ/4) resonance system, it is possible to restraindeterioration of antenna characteristics of the (λ/2) resonance system,which is caused by holding the cellular phone terminal by a hand. As thefrequency is raised further, propagation loss becomes larger. Thus, ifthe higher frequency in a plurality of the frequencies is used for the(λ/2) resonance system, antenna characteristics at the time of use ofthe human body can be improved.

[0071] The monopole antenna is not necessarily used exclusively forreception. In this embodiment, the monopole antenna is used incombination with the external antenna by way of example but can be,needless to say, used for both transmission and reception. In this case,it is possible to perform diversity reception by combining the monopoleantenna with another built-in antenna.

[0072] Meanwhile, position of the external antenna is not restricted tothe illustrated one and only the built-in antenna may be naturallyemployed by eliminating the external antenna.

[0073] (Sixth embodiment)

[0074] Hereinafter, a sixth embodiment of the present invention isdescribed with reference to FIGS. 12A and 12B in which parts similar tothose of FIGS. 1A and 1B and FIGS. 11A and 11B are designated by theirreference numerals. FIGS. 12A and 12B show an example of an arrangementof a cellular phone terminal according to the sixth embodiment of thepresent invention. In FIGS. 12A and 12B, “12011” denotes a portableradio device, “1202” a first antenna element, “1203” a second antennaelement, “1204” a flexible printed wiring board, “1205” a first antennafeeding point and “1206” a second antenna feeding point.

[0075] As an example, a case is described in which the antennas act as(λ/4) monopole antennas at the two frequencies f1 and f2, respectively.In this case, the frequencies f1 and f2 are not required to satisfy therelation of (2f1≈f2). In case the cellular phone terminal is operated atthe frequency f1, a length of the first antenna element 1202 and a firstconductive pattern 1204a on the flexible printed wiring board 1204 ispreset at an electric length of about (λ/4). At the time oftransmission, a signal having the frequency f1 and inputted from thefirst antenna feeding point 1205 is radiated to space from the firstconductive pattern 1204 a on the flexible printed wiring board 1204 andthe first antenna element 1202. At the time of reception, a receptionsignal having the frequency f1 and delivered from the first antennaelement 1202 and the first conductive pattern 1204 a on the flexibleprinted wiring board 1204 is inputted from the first antenna feedingpoint 1205 to a reception circuit.

[0076] In case the cellular phone terminal is operated at the frequencyf2, a length of the second antenna element 1203 and a second conductivepattern 1204 b on the flexible printed wiring board 1204 is preset at anelectric length of about (λ/4). At the time of transmission, a signalhaving the frequency f2 and inputted from the second antenna feedingpoint 1206 is radiated to space from a second conductive pattern 1204 bon the flexible printed wiring board 1204 and the second antenna element1203. At the time of reception, a reception signal having the frequencyf2 and delivered from the second antenna element 1203 and the secondconductive pattern 1204 b on the flexible printed wiring board 1204 isinputted from the second antenna feeding point 1206 to the receptioncircuit.

[0077] By using a plurality of the antenna elements and the conductivepatterns selectively as described above, the cellular phone terminal iscapable of dealing with a plurality of frequency bands. By setting thelength of the antenna element and the conductive pattern at an electriclength of about (λ/4) in each frequency band, it is possible to obtainwide-band characteristics in each frequency band.

[0078] In this embodiment, the two antennas are provided but the numberof the antenna is not restricted to two. Thus, at least two antennas maybe employed as constituent elements.

[0079] Meanwhile, in this embodiment, each of both of the two antennasincludes as its constituent element the antenna element on the upperprinted board but the present invention is not restricted to thisarrangement. Hence, at least one of a plurality of the antennas mayinclude as its constituent elements the antenna element on the upperprinted board and the conductive pattern on the flexible printed wiringboard.

[0080] Furthermore, in this embodiment, only a case in which theelectric length is about (λ/4) has been described but the presentinvention is not restricted to this case. Also in the case where theelectric length is about (λ/2), it is likewise possible to cope with aplurality of the frequency bands by using a plurality of the antennaelements and the conductive patterns. In this case, electric currentflowing through the housing and the board can be lessened and antennacharacteristics at the time of use of the human body are probablyimproved.

[0081] Meanwhile, it is, needless to say, possible to use by combiningat least two of cases in which the electric length of the antennaelement and the conductive pattern is about (λ/4), (λ/2) and (3λ/4). Forexample, in case a composite device of the PDC system having a 800-MHzband and a 1.5 MHz band is materialized, it is naturally considered thatin the 800-MHz band having a quite wide fractional band of about 17%,the composite device functions as a (λ/4) monopole antenna in order toobtain wide-band characteristics and in the 1.5-MHz band having acomparatively narrow fractional band of about 5%, the composite devicefunctions as a (λ/2) monopole antenna in which deterioration ofcharacteristics at the time of use of the human body can be lessened.

[0082] Meanwhile, in case the (λ/4) monopole antenna and the (λ/12)monopole antenna are arranged side by side, a feeding point of the (λ/4)monopole antenna is disposed at an antinode of standing wave of electriccurrent but a feeding point of the (λ/2) monopole antenna is disposed ata node of standing wave of electric current, so that electromagneticcoupling becomes smaller than a case in which the two (λ/4) monopoleantennas are arranged side by side and thus, isolation of the antennasfrom each other can be improved.

[0083] Meanwhile, in case a plurality of the antenna elements and theconductive patterns are arranged adjacent to each other, such a problemarises that isolation of the antennas from each other deteriorates.However, this problem may be solved by, for example, an arrangementshown in FIGS. 13A and 13B in which the antennas are arranged away fromeach other physically. Meanwhile, parts similar to those of FIGS. 1A,1B, 11A, 11B, 12A and 12B are designated by their reference numerals.

[0084] In FIGS. 13A and 13B, “1301” denotes a portable radio device,“1302” a first antenna element, “1302” a second antenna element and“1304” a flexible printed wiring board. In this case, it is importantthat a first conductive pattern 1304 a and a second conductive pattern1304 b are disposed at outermost portions so as to be farthest from eachother in the flexible printed wiring board 1304. Meanwhile, since theantenna elements are disposed away from each other on the upper printedboard 104, electromagnetic coupling therebetween weakens further, sothat it is expected that isolation therebetween can be improved.

[0085] Meanwhile, as in an arrangement shown in FIGS. 14A, 14B and 14C,it is considered that antenna elements are disposed further away fromeach other. Meanwhile, parts similar to those of FIGS. 1A and 1B andFIGS. 11A and 11B to FIGS. 13A and 13B are designated by their referencenumerals.

[0086] In FIGS. 14A, 14B and 14C, “1401” denotes a cellular phoneterminal, “1402” a land pattern, “1403” a first antenna element, “1404”a second antenna element and “1405” a spring contact point. At thistime, the second antenna element 1404 disposed in the upper housing 101is electrically connected to the land pattern 1402 on the upper printedboard 104 via the spring contact point 1405 and is connected to thefirst feeding point 1205 through the first conductive pattern 1304 a ofthe flexible printed wiring board 1304. In this case, since the secondantenna element 1404 is disposed at an inside of the upper housing 101,the second antenna element 1404 can-be spaced away from the firstantenna element 1403, so that it is expected that isolation therebetweencan be improved. Meanwhile, if a low-frequency antenna is constituted bythe second antenna element 1404, the spring contact point 1405, the landpattern 1402 and the first conductive pattern 1304 a, the antenna can bespaced away from a head at the time of use of the human body, so thatnot only deterioration of antenna characteristics can be restrained buta specific absorption rate (SAR) value can be reduced. In case it isintended to lower the SAR value, peak value of the SAR generally risesas frequency becomes higher. Therefore, by disposing a high-frequencyantenna into the housing, the SAR value can be reduced effectively.

[0087] In order to improve isolation between the antennas, anothermethod is considered in which a matching circuit is used as shown inFIGS. 15A and 15B. Meanwhile, parts similar to those of FIGS. 1A, 1B,11A, 11B, 12A and 12B are designated by their reference numerals.

[0088] In FIGS. 15A and 15B, “1501” denotes a portable radio device,“1502” a first matching circuit and “1503” a second matching circuit. Asone example, a case is described in which two (λ/4) monopole antennasoperate at frequencies f1 and f2, respectively. It is supposed here thatwhen the first antenna element 1202 and the first conductive pattern1204 a resonate at the frequency f1 and the second antenna element 1203and the second conductive pattern 1204 b resonate at the frequency f2,the relation of (f1<f2) is satisfied. In this case, it is consideredthat the first matching circuit 1502 inserted between the firstconductive pattern 1204 a and the first antenna feeding point 1205 isformed by a low-pass filter. Thus, a signal emitted into space from thesecond antenna element 1203 and the second conductive pattern 1204 b andhaving a frequency higher than the frequency f1 is less likely to bereceived by the first antenna element 1202 and the first conductivepattern 1204 a. Therefore, in a signal inputted from the first antennafeeding point 1205, a signal component having a frequency higher thanthe frequency f1 is damped by the first matching circuit 1502, so thatisolation is improved. Meanwhile, it is natural that the same effect canbe gained also when the first matching circuit 1502 is formed by ahigh-stop filter.

[0089] Meanwhile, it is considered that the second matching circuit 1503inserted between the second conductive pattern 1204 b and the secondantenna feeding point 1206 is formed by a high-pass filter. Thus, asignal emitted into space from the first antenna element 1202 and thefirst conductive pattern 1204 a and having a frequency lower than thefrequency f2 is less likely to be received by the second antenna element1203 and the second conductive pattern 1204 b. Therefore, in a signalinputted from the second antenna feeding point 1206, a signal componenthaving a frequency lower than the frequency f2 is damped by the secondmatching circuit 1503, so that isolation is improved. Meanwhile, it isnatural that the same effect can be achieved also when the secondmatching circuit 1503 is formed by a low-stop filter.

[0090] Meanwhile, the monopole antenna is not necessarily usedexclusively for reception. In this embodiment, the monopole antenna isused in combination with the external antenna by way of example but canbe, needless to say, used as an antenna for both transmission andreception. In this case, it is possible to perform diversity receptionby combining the monopole antenna with another built-in antenna.

[0091] Meanwhile, position of the external antenna is not restricted tothe illustrated one and only the built-in antenna may be naturallyemployed by eliminating the external antenna.

[0092] As is clear from the foregoing description of the cellular phoneterminal of the present invention, since the monopole antenna isconstituted by the conductive pattern on the flexible printed wiringboard and the conductive pattern on the printed board, electric currentflowing through the antenna element on the flexible printed wiring boardcan be made smaller than a case in which only the conductive pattern onthe flexible printed wiring board is used as an antenna, so that changesof characteristics of the cellular phone terminal upon its unfolding andfolding can be restrained and introduction of noise into other signalconductor lines can be restricted.

[0093] Meanwhile, if the signal conductor lines except for the antennaof the flexible printed wiring board is formed by a microstrip line or atriplate line, the influence of noise introduction exerted by theantenna can be restrained.

[0094] Furthermore, if the recessed finger grip portion is provided onthe lower housing, only the lower housing can be gripped withoutgripping the upper housing when the cellular phone terminal is held by ahand, so that deterioration of antenna characteristics in hand-heldstate of the cellular phone terminal can be prevented.

[0095] In addition, if the flexible printed wiring board is providedsuch that the monopole antenna is spaced away from the external antenna,coefficient of correlation of the external antenna and the monopoleantenna is reduced, so that diversity gain can be improved.

[0096] Meanwhile, since the antenna functioning as the antenna of the(λ/4) resonance system is capable of functioning as the antenna of the(λ/2) resonance system upon changeover of the matching circuit, it ispossible to cover a plurality of frequency bands. Meanwhile, if aplurality of the antennas are formed by a plurality of the antennaelements and the conductive patterns, it is possible to cover aplurality of frequency bands. In this case, if the antennas are spacedaway from each other or the matching circuit is inserted, isolation canbe improved and antenna characteristics can be improved.

1. A cellular phone terminal comprising: an upper housing which includesan upper printed board; a lower housing which includes a lower printedboard; a hinge; and flexible printed wiring board; wherein the upperprinted board and the lower printed board are foldably connected to eachother by the flexible printed wiring board and the upper housing and thelower housing are rotated to each other about the hinge such that thecellular phone terminal is foldable; wherein unbalanced type linearantennas are formed on the flexible printed wiring board and at leastone of the upper printed board and the lower printed board.
 2. Acellular phone terminal as claimed in claim 1, wherein the flexibleprinted wiring board is constituted by a strip line including a groundline and a signal conductor line, and a further signal conductor linefunctioning as an antenna.
 3. A cellular phone terminal as claimed inclaim 1, wherein the flexible printed wiring board is constituted by atriplate line including two ground lines and a signal conductor lineinterposed between the ground lines, and a further signal conductor linefunctioning as an antenna.
 4. A cellular phone terminal as claimed inone of claims 1 to 3, wherein a hollow is formed at a central portion ofthe hinge and one turn of the flexible printed wiring board is passedalong an inside diameter of the hollow.
 5. A cellular phone terminal asclaimed in claim 4, further comprising: an external antenna for bothtransmission and reception, which is provided on the lower housing suchthat a point of connection between the flexible printed wiring board andthe lower printed board is disposed more adjacent to the externalantenna than a point of connection between the flexible printed wiringboard and the upper printed board is.
 6. A cellular phone terminal asclaimed in one of claims 1 to 5, wherein the linear antennas are formedon the upper printed board and the flexible printed wiring board and thelinear antennas are fed from a feeding point on the lower printed board.7. A cellular phone terminal as claimed in one of claims 1 to 6, furthercomprising: a switching circuit; and a plurality of matching circuits ofthe linear antennas, which are changed over by the switching circuit. 8.A cellular phone terminal as claimed in claim 7, wherein the linearantennas have an electric length equal to about (¼) of their wavelengthand each function as a (λ/2) resonator for a wavelength of a differentfrequency band upon changeover of the matching circuit.
 9. A cellularphone terminal as claimed in one of claims 1 to 8, wherein at least twofurther linear antennas are formed on the flexible printed wiring boardand at least one of the upper printed board and the lower printed boardand resonate at different frequencies, respectively.
 10. A cellularphone terminal as claimed in claim 9, wherein the further linearantennas include at least two of an antenna having an electric lengthequal to (¼) of its wavelength, an antenna having an electric lengthequal to about (½) of its wavelength and an antenna having an electriclength equal to (¾) of its wavelength.
 11. A cellular phone terminal asclaimed in claim 9 or 10, wherein the two further linear antennas formedon the flexible printed wiring board are, respectively, disposed atopposite outermost sides.
 12. A cellular phone terminal as claimed inone of claims 9 to 11, wherein at least one of the further linearantennas includes a linear element disposed on an inner face of theupper housing or an inner face of the lower housing.
 13. A cellularphone terminal as claimed in one of claims 9 to 12, wherein one of thefurther linear antennas has a lowest resonance frequency in the furtherlinear antennas and is connected to a feeding point via a low-passfilter.
 14. A cellular phone terminal as claimed in one of claims 9 to13, wherein a further one of the further linear antennas has a highestresonance frequency in the further linear antennas and is connected to afeeding point via a high-pass filter.
 15. A cellular phone terminal asclaimed in one of claims 9 to 12, wherein one of the further linearantennas has a lowest resonance frequency in the further linear antennasand is connected to a feeding point via a high-stop filter.
 16. Acellular phone terminal as claimed in one of claims 9 to 12, wherein oneof the further linear antennas has a highest resonance frequency in thefurther linear antennas and is connected to a feeding point via alow-stop filter.
 17. A cellular phone terminal foldable into twosections, comprising: a lower housing which is provided with a recessedfinger grip portion.
 18. A cellular phone terminal as claimed in one ofclaims 1 to 16, which is foldable into two sections, wherein the lowerhousing is provided with a recessed finger grip portion.